Checking
CAUTIONAll work on vehicle calling for running engine must be done with selector lever at N or P and parking brake applied. Only exceptions are pressure test and stall speed test
Note
For proper transmission operation engine idle speed, ignition timing, etc. must be correct
Poor engine output because of incorrect adjustments or bad parts may give impression of problems with automatic transmission
Before checking operation, try to get information on how problem occurred and whether any repairs were performed previously
Trouble is often caused by incorrectly adjusted selector lever cable/accelerator cable, low ATF level or poor engine adjustment
Before starting repairs perform general checks and road test
A - General Checks
- check engine idle speed, ignition timing
- check for leaks (ATF or hypoid oil), external damage, loose or missing screws, etc.
B - Transmission fluid level/final drive oil level, checking
- check that vehicle is level
- place selector lever in P and apply parking brake. Idle engine. ATF must be lukewarm
- check that ATF level is between two marks on dipstick
- difference between upper and lower mark is approx. 1 pint
- oil level may be above or below mark depending on ATF temperature (heat expansion of ATF)
CAUTION
Tiny particles, dirt, or even lint can clog transmission valves. Use only clean funnel and hose to add ATF and only wipe dipstick with clean lint-free cloth
- do not overfill because too much fluid will upset operation of transmission
- check smell and appearance of ATF. ATF with burnt smell may indicate burnt friction linings and trouble in control system
CAUTION
Only automatic transmission fluids labeled I DEXRON© or DEXRON II© must be used. All approved ATFs can be mixed with one another. Do not use additives
C - Final drive oil level, checking
- final drive oil level must be up to edge of oil filler hole
- if level is too high or too low it may indicate transfer of oil between transmission and final drive
D - Stall speed test
Note
Check stall speed only if vehicle shows poor performance or poor acceleration
- engine must be warm. Connect tachometer
- start engine and hold vehicle firmly with parking brake and foot brake
- put selector lever in D and depress accelerator pedal briefly to full throttle
- check that engine now runs between
Trans code letter
TJ = 2200 to 2500 RPM
TNA = 2320 to 2570 RPM
CAUTION
Do not continue stall speed test longer than time to read tachometer. Maximum stall speed test time 20 seconds. Operating at stall speed for longer than 20 seconds will overheat torque converter
Note
Normal stall speed will drop 125 rpm per 3200 ft altitude. Stall speed will also drop slightly at high ambient air temperature
- if stall speed is not as specified following items may be wrong:
E - Road test
Note
Vehicle should be driven in all gear ranges and under all possible road conditions. Do not road test if there is obvious mechanical damage
- note shift points and compare to chart above. Shifts should be smooth. Shifts should take place quickly and without lag in power transmission
- listen for any sign of engine speedup between shifts. Speedup between shifts indicates slipping brake bands or clutches
- after road test check transmission for fluid leaks
Note
If shift points are incorrect or transmission does not kickdown, check accelerator cable adjustments
F - Pressure test
Note
Only if defect cannot be found during other checks should a pressure test be carried out. This test will locate defects in ATF circuit (internal leakage, wear, sticking control valves or dirt in ATF system)
- gauge connection (arrow)